Crimping apparatus



J. .LHElJNls Erm. 2,949,659

Aug. 23, 1960 CRIMPING APPARATUS Filed May 1s, 1957 United States Patent CRIB/[PING APPARATUS James Watt Ijsbrand Heijnis and Conrad Joseph Gonsalves, Arnhem, Netherlands, assignors to American Enka Corporation, Enka, N.C., a corporation of Delaware Filed May 13, 1957, Ser. No. 658,779 Claims priority, application Netherlands May 24, 1956 14 Claims. (Cl. 'Z8- 1) The present invention relates generally to the preparation of ber for commercial use and more particularly to an improved apparatus for crimping thermoplastic thread according to the stuier box principle.I

It is known to impart crimp to a continuous thermoplastic thread by feeding the same into the chamber of a stuffer box against the action of a mechanical pressure or restriction. The thread usually is fed into a heated portion of the stuffer box by driven feed rollers, cooled in another portion of the box and finally withdrawn therefrom by thread discharge means, which also could be driven rollers. A stuifer box of this general type is shown and described in U.S. Patent No. 2,311,174, dated February 16, 1943.

In the crimping of thread according to the known system described above, thread forced into the chamber of the stutfer box loops back upon itself until a wad is formed at the entrance end of the chamber, which wad progressively grows in the direction of the discharge end as more thread is fed into the chamber, and which produces crimps in the continuous thread. The crimped thread is withdrawn from the stuffer box at a rate proportionate to the rate of infeed. A pivoted clapper plate usually is resiliently urged into the path of travel of the thread and restricts passage thereof to the extent that the wad is formed.

While the aforesaid known apparatus operates to produce satisfactory crimps in continuous thread, there are certain disadvantages which render use thereof objectionable. For example, upon starting or threading-in of the known stutfer box, extreme care must be taken lest the leading portion of thread wrap around the feed rollers rather than pass freely into the open restricting chamber. Attempts at preventing this occurrence by the use of knife edges which scrape against the feed rollers have not proved completely successful. Additionally, it has been found that the thread forced into a wad frequently becomes so thoroughly entangled as to prevent withdrawal of the same from the stuifer box in a single continuous crimped tow or bundle. Such entanglements are Very undesirable since the crimped thread usually is fed into a cutting means for severance into predetermined equal staple lengths. Accordingly, full attention of an operator is required to obviate this undesirable situation even after threading-in has been successfully accomplished.

One of the objects of this invention is to provide an apparatus for crimping thread not having the inherent disadvantages of known crimping devices.

Another object of the present invention is to provide a novel apparatus for preventing wrap of thread around the feed rollers during and subsequent to threading-in of a stuffer box.

A further object of this invention is to provide a novel apparatus for resisting passage of thread into and through the stuffer box, thereby forming a wad.

Still another object of the present invention is to provide a novel apparatus for restricting passage of thread through a stuifer box while preventing wrap of the thread around the feed rollers.

Another object of this invention is to provide a novel apparatus for preventing wrap of thread around feed rollers of a stuifer box while restricting passage of the thread through the crimping chamber of said box.

In accordance with the present invention, a stuffer box having a vertical chamber therein is mounted in cooperative relationship above a pair of positively driven feed rollers. The mechanical pressure means for resisting passage of the thread through the chamber is formed,

' at least in part, by a plurality of balls, the diameters of which are such that at least :that portion of each feed roller which projects into the chamber. Moreover, a suicient number of these balls are placed within the chamber to lill the same above the level of the exposed feed roller surfaces and to completely cover the chamber and wad which subsequently is formed therein at the smallest cross-section thereof.

The balls situated in the stuifer box chamber are multipurpose and therefore perform various functions in the presently described crimping process. The primary function is to prevent the leading portion of thread from wrapping around the feed rollers upon threading in of the stuffer box. This is accomplished by virtue of the deecting action of the balls yon the thread, which prevents the thread from passing into the joint formed between the stufer box walls and the peripheral edges -and end surfaces of the feed rollers. During formation of a wad from the thread continuously supplied tothe chamber the balls are forced upwardly and thereby spread into a layer which rests on the thread wad. As soon as the thread wad has reached the desired height, withdrawal can begin and crimped thread is released from the chamber and passed through a thread discharge means to a take-up device. It has been found that the balls promote a uniform release of the crimped thread from the wad without the occurrence of undesirable entanglements, this second function being caused by the frictional action exerted on the thread by the balls.

Other objects and advantages will become apparent upon consideration of the following detailed description of a preferred embodiment taken in conjunction with the accompanying drawings, wherein:

Figure l is aperspective View of a stuifer box constructed in accordance with the present invention;

Figure 2 is a vertical sectional view, on an enlarged scale, of the Adevice shown in Figure 1 at the beginning of the crimping operation;

Figure 3 is a vertical sectional view, taken along the lines 3 3 of Figure 2, and showing the position of the balls during normal operation of the stuffer box; and

Figure 4 is a plan view, partly in section, taken along the lines 4-4 of Figure 3.

With attention now directed to Figure 1 of the drawings, reference numeral 10 designates generally a crimping device or stuifer box according to the present invention, which device may be supported in conventional manner from a frame (not shown). Thread 11 is fed into and through the stuifer box in the direction of the arrows by feed rollers 12. The feed rollers 12 are urged into engagement with one another by the use of known means, such as a spring (not shown), and are positively rotated through shafts 13 by any suitable drive means (also not shown).

The stuifer box 10 comprises a tubular member 14 on the outside of which extends vertical cooling ribs or fins 15. The tubular member 14 is vertically yarranged so that the center line or axis thereof is in alignment with the nip of feed rollers 12. In order to ensure a snug tit between the tubular member and the peripheral and lateral surfaces of the feed rollers over which the member is positwo balls may rest on tioned, the lower portion of the former member is provided with a diametrical notch defined by extensions 16, as can be seen upon inspection of Figures 1 and 3. The extensions 16 thereby close two sides of the wedge-shaped throat 17 between rollers 12, the remaining sides being closed by the peripheral surfaces of said rollers extending above the line of contact therebetween.

The upper edges 13 of the diametrical notch in member 14 are beveled, as shown in Figure 2, in order that the same will t smoothly and snugly against the aforesaid peripheral surfaces of rollers 12. A helical compression spring Ztl is provided to urge the tubular member continuously and resiliently against the rollers. The spring 20 is clamped between a supporting plate 21, within which tubular member 14 is slidably mounted, and an annular chamber 22 which is fixed to the stufer box. The plate 21 may be iixed to the frame of the crimping device in any known manner.

The interior of the annular chamber 22 communicates by way of discharge pipe 23 to any suitable type of suction device (not shown) land further communicates with the interior or crimping chamber of stulfer box through a series of radial channels 24. Above the horizontal plane in which the channels 24 open into the crimping chamber, the latter is provided with a lining 25 formed from polytetrauoroethene, for a purpose to `appear herinafter. The discharge or upper end of the crimping chamber is closed with a cap 26 having a thread passageway 27 centrally located therein.

The crimping chamber of tubular member 14 is partially filled with balls 28, as can be seen from the drawings. The diameter of said balls in relation to the peripheral surface of feed rollers 12 which extend into the crimping chamber is such that at least two balls may rest against the surface of each-roller, with a total of at least four balls contacting the feed rollers and resting adjacent one to the other. A ball diameter of 1.5 mm. and a crimping chamber diameter of 6.5 mm. have proved satisfactory for this purpose.

The stutter box or crimping device 10 is further provided with a tubular heating device indicated generally at 30 which is arranged vertically beneath the feed rollers 12. This device comprises a central small diameter tube 31 open at both ends, thus forming a thread passageway, and a larger diameter air supply tube 32 which coaxially surrounds the small inner tube. The larger outer tube 32 is attened at the upper end thereof in such a manner that the sides contact the inner tube 31, as can be seen upon inspection of Figures 2 and 3. Consequently, two outlet openings 33, extending on either side of the inner tube, are provided in the upper end of air supply tube 32. Air may be supplied to the outer tube 32 by a pipe 34 connected to the lower end of this tube.

The tubular heating device 30 further comprises a heating element 35 which coaxially surrounds the tubes 31 and 32 and an exterior insulating casing 36. The heating element is connected in known manner to a source of energy, such as the electrical means shown. The entire tube system is arranged so that the upper mouth of the inner tube 31 and the outlet openings 33 of the outer tube 32 are juxtaposed just beneath the nip or line of contact between feed rollers 12. As mentioned hereinabove, any suitable means (not shown) may be provided for Withdrawing thread from the crimping chamber. Such means should be positioned above and preferably in alignment with the thread passageway 27 in cap 26.

In the operation of the device described above, thread 11 to be crimped is led from a suitable supply source (not shown) beneath the stuffer box in an upward direction through the inner tube 31, between feed rollers 12, through the tubular member 14 and finally through the thread passageway 27 onto suitable discharge means. As a result of the central position of the inner tube 31 with respect to rollers 12, balls 28 will lie on either side of the thread 11, preferably with two balls on each side, as viewed in Figure 2.

As soon as threading in has been accomplished, the feed rollers are brought into rotation, the heating element 35 is switched on and the device for supplying air to the outer tube 32, as well as the suction device for withdrawing air from annular chamber 22 are put into operation.

It should be noted that the suction created in discharge pipe 23 of the annular chamber is such that not only is heated air withdrawn from outer tube 32 but air also is sucked into and through the crimping chamber from thread passageway 27 in a direction countercurrent to the direction of travel of thread 11. In this manner of air ilow, and by virtue of fins SLS on the exterior of tubular member14, the thread is cooled before it is released from the thread wad indicated at 37. From the thread initially supplied tothe feed rollers this thread wad 37 is formed by looping back of layers in -a manner explained hereinabove. As additional thread is forced into the crimping chamber, the Wad progressively increases in size,

pushing the balls 28 upwardly from the position shown in Figure 2 to that shown in Figure 3. At the beginning of Wad formation, the thread also forces the balls in a lateral direction, thus closing off openings between the extensions 16 of tubular member 14 and the peripheral and end surfaces of the feed rollers, thereby preventing passage of thread therein which subsequently would result in wrap of the thread `about the feed rollers.

A second function performed by the balls 28 is that of determining the mechanical pressure which resists passage of thread into the crimping chamber. This pressure or resistance, which heretofore has been accomplished by a clapper or baffle plate, as mentioned supra, in combination with the action of feed rollers 12, creates the thread loops which form wad 37. The thread wad 37 is subjected to the action of heated air drawn into the crimping chamber through outer tube 32, outlet openings 33, and between the feed rollers 12. It has been found that heating of this air to approximately C. facilitates -thc crimping action and causes a fixation of the thread in crimped condition.

As soon as the thread wad 37 has grown to the desired height whereby an optimum crimping effect is ensured, the thread discharge device is put into operation, as a result of which Athread 1l is unwound from wad 37 at a rate proportionate to the speed of travel through feed rollers 12. The balls 23 are rotated by the thread traveling therethrough and thereby exert a frictional action on the upper portion of the wad, which expedites release of thread from the wad without undesirable entanglements, as mentioned earlier in this disclosure.

The lining 25, which preferably consists of polytetrafluoroethene, facilitates sliding movement of the thread wad 37 through the crimping chamber and permits accumulation of a relatively large amount of thread in wad form, which consequently subjects the thread to a xation in crimped condition for a longer period of time. This results in an improved and more durable crimp.

It has been found that balls 28 perform both of the aforesaid functions with a very satisfactory result if the thread supplied thereto does not exceed 1,000 denier. With a higher denier thread the effect of the balls is present, but to a lesser extent.

The diameters of the balls may Vary within wide limits, but a principal condition is that -two balls should rest against each other on that surface of each feed roller which projects into the crimping chamber. If this condition exists, the thread is prevented from wrapping around the feed rollers, as explained above. It is preferred, however, that such a ratio between ball diameter and crimping .chamber dimension in the direction of the nip line be chosen as to allow four balls to lie adjacent one to another on each roller.

In order to provide for an effective release of thread from the thread wad during a crimping operation it is necessary that at least one complete layer of balls rest above the wad. It is possible, of course, to provide additional layers of balls, as indicated in the drawings. If

' above the wad.

The physical characteristics of the stuffer box may vary to correspond with particular requirements. For example, the crimping chamber may be square, rectangular, circular, etc., in cross-section and in the longitudinal direction may be conical or provided with constrictions. A cylindrical stuifer box, however, is preferred. Moreover, it is preferred that the ycylindrical crimping chamber of this box be approximately 6.5 mm. in diameter and that balls having an individual diameter of 1.5 mm. be placed within the chamber. Consequently, four balls will rest next to one another and above the nip of the feed rollers.

In order to prevent thread from running olf the ends of respective feed rollers 12, 12, streams of air are directed into the stuffer box from both sides of the thread, as shown in Figure 3. It is preferred that this air be heated in order to facilitate retention of the crimps by preventing cooling of the stuffer box near the feed rollers. The two streams of air have the same guiding effect as the balls during threading-in of the stuifer box. If desired, the air streams may be directed into the crimping chamber immediately above the feed rollers. Moreover, if desired, known mechanical means, in addition to the balls, may be provided for exerting pressure on the thread wad.

As a Speciiic example of operation, a 100 denier, 35 filament thread consisting of polyaminocapronic acid was led through the inner tube 31 and between the feed rollers 12 at a velocity of 140 m./min. Air was passed through the supply pipe 34 and into the outer tube 32 at a rate of 6 liters 'per minute, and was heated to a temperature of 160 C. by the heating element 35. The crimping chamber was cylindrical and had a cross-section of 33 mm?.

A thread wad 37 having a height of approximately 120 mm. was maintained above the feed rollers and the thread was kept in crimped condition for about 60 seconds. The radial channels 24 opened into the crimping chamber at a height of 16 mm. above the line of Contact between the feed rollers. Air was withdrawn from the crimping chamber under a vacuum of 50 mm. of water. In the starting position, the height of the pile of balls was about 30 mm. An elastic thread having a very satisfactory woolly feel was obtained.

In order to obtain a strong or more permanent crimp, it may -be desirable to provide a supplementary heating device for further heating the lower portion of the stuffer box. As an example, heated air may be fed into the chamber above the feed rollers, as mentioned supra. The temperature of air forced into the chamber at this point may be raised to the required level by a heating device arranged above the feed rollers, and the temperature may be equal to or higher than that of the air supplied through air supply tube 32; for instance, the supplementary air may be raised to a temperature of about 190 C.

If it is desired that heated air be supplied to the crimping chamber above the feed rollers, the same may be blown in through the annular chamber 22. Consequently, all of the heated air, together with cool air entering through passageway 27 and flowing countercurrent to the direction of thread travel, may be withdrawn at some point above the supplementary heating device but below the top of the thread wad. It is of course possible to omit the tubular heating device 30 and to rely solely on the aforesaid supplementary heating system, or to heat the stutter box in a different manner.

In the embodiment described, a pile of balls is used to determine the entire mechanical pressure against which the thread is forced into the crimping chamber. It is generally necessary that this pile have a height of at least 3 cm. in order that the weight thereof be sufficient to produce a wad, the pressure being determined by the weight of the balls and the friction exerted on the balls and thread wad by the interior surface of the chamber. As mentioned above, however, this pressure may be supplemented by a piston mounted within the crimping chamber and having an axial passageway for the discharge Aof thread. Although the use ofa piston would permit reduction in the number of balls provided, it is still necessary that a sufficient number of balls be present to cover the surface of the wad and to prevent wrap of thread about the feed rollers. Additionally, balls 28 having a diameter greater than 1.5 mm. obviously could be used, provided that the previously mentioned condition obtain, i.e., that at least an even number of balls be allowed to rest next to onaanother above the nip of each feed roller. A

While a preferred embodiment has been described in order to illustrate the principles involved, it should be understood that the present invention is limited only to the extent defined in the following claims.

What is claimed is:

l. A device for crimping thread comprising-a tubular member dening a crimping chamber, a pair of rollers for feeding thread into said chamber and a plurality of balls positioned within said chamber for preventing wrap of thread about said feed rollers and for resisting passage of thread through the crimping chamber.

2. A device for continuously crimping thermoplastic thread comprising a stuffer box having a crimping chamber,means for feeding thread into said chamber, means for resiliently urging one end of said stuer box into cooperative relationship with said feed means, and means within said chamber for resisting passage of thread through the crimping chamber to the extent necessary for forming a wad and for simultaneously promoting a uniform release of crimped thread from said wad without the occurrence of entanglements.

3. A device for continuously crimping thermoplastic thread comprising a stuifer box having a crimping chamber, a pair of cooperating rollers for feeding thread into said chamber, means for supplying heated air Iat the line of contact between said cooperating feed rollers and on both sides of the thread passing therethrough and a plurality of balls positioned within said chamber for preventing wrap of thread about said feed rollers and for resisting passage of thread through the crimping chamber.

4. A device for crimping thread comprising a stuffer box having a crimping chamber, said crimping chamber being lined with polytetrafluoroethene, a pair of rollers forfeeding thread into said lined chamber and a plurality of balls positioned within said chamber for preventing wrap of'thread about said feed rollers and for resisting passage of thread through the lined crimping chamber.

5. In a device for continuously crimping thermoplastic thread comprising a stuier box having a crimping charnber, a pair of rollers for feeding thread to said chamber, means for withdrawing thread from said chamber and means for applying mechanical pressure on the thread fed into said chamber by said feed rollers, the improvement which comprises a plurality of balls positioned within said chamber for forming at least part of said means for applying mechanical pressure to the thread and for preventing wrap of thread about said feed rollers.

6. A device for continuously crimping thermoplastic thread comprising a tubular member defining a crimping chamber, a pair of cooperating rollers for feeding thread into said chamber, means for urging one end of said tubular member into cooperative relationship with said feed rollers and a plurality of balls positioned within said chamber for preventing wrap of thread about said feed 7 rollers and for applying at least some resistance sage of thread through the crimping chamber.

7. A .crimping device as set forth in claim 6 wherein the diameter of said balls with respect to the point of smallest cross-section of said crimping chamber is such that at least four balls may rest adjacent to one another in a common plane at this point.

8. A device for continuously crimping thermoplastic thread comprising a tubular member dening a crimping chamber, extensions at one end of said tubular member defining a diametrical notch, a pair of cooperating rollers for feeding thread into said crimping chamber, means for resiliently urging said tubular member into cooperative relationship with said feed rollers with portions of the latter snugly tting into said diametrical notch and a plurality of balls positioned within said chamber for preventing wrap of thread about said feed rollers and for applying at least some resistance to passage of thread through the crimping chamber.

9. A crimping device as set forth in claim S wherein the diameter of said balls with respect to the crosssec tion of said crimping chamber is such that at least two balls may contact that portion of each feed roller which projects into said notch.

10. A crimping device as set forth in claim 9 wherein to pas- 8 Y the number of balls positioned Within said chamber is suflcient to ll the same above the upper surfaces of said feed rollers .and to cover the chamber at the point of smallest .cross-section with at least one closed layer.

11. A crimping device as set forth in claim 9 wherein the crimping chamber is lined with polytetratluoroethene.

12. A crimping device as set forth in claim 8 wherein means is provided for supplying heated air at the line of Contact between said cooperating feed rollers and on both sides of the thread passing therethrough.

13. A crimping device as set forth in claim 12 wherein means is provided for withdrawing said heated air and for withdrawing cooling air in a direction countercurrent to the direction of thread travel through said tubular member.

14. A crimping device as set forth in claim 13 wherein cooling iins extend longitudinally of said tubular member.

References Cited in the tile of this patent UNITED STATES PATENTS 

